Recent events in Ukraine, Syria, and Iran exposed once again a deep divide in American policymakers’ approach to world affairs. President Obama hails his determined diplomacy as the vindicator of events, bringing Iran and Syria to the negotiating table and isolating Russia for practicing 19^th-century military intervention in Ukraine. Throughout, Obama keeps the potential use of force under, if not off, the table, ruling out any military options until negotiations fail. His critics argue just as strenuously that Obama’s diplomacy does little more than buy time for aggressive nations like Iran and Russia to accomplish their objectives outside negotiations by...